A device for supplying a medical apparatus with liquid anesthetic has become known from DE 35 23 948 C2. A reservoir of modular design for liquid anesthetic is connected to an anesthesia apparatus in such a way that the reservoir is pushed into the apparatus along a guide. The reservoir is provided with a code, which enables the user to determine which anesthetic is being fed to the anesthesia apparatus by the reservoir being used. In addition, an anesthetic-specific filling device and a filling level indicator are located at the reservoir. In the coupled state of the reservoir, the anesthetic enters a metering device within the anesthesia apparatus via a nonreturn valve and a tapping connection. The tapping connection, which is part of the anesthesia apparatus, opens the nonreturn valve located in the reservoir on coupling, so that the anesthetic can reach the metering device. The desired amount of anesthetic is provided by means of the metering device, which may be designed as a metering pump.
The drawback of the prior-art device is that when the anesthetic is changed, the previous anesthetic is still being metered for some time, because it is still present in the connection line between the tapping connection and the metering device, while the anesthetic to be administered as a new anesthetic will be available only after the residual amount has been used up.